Williams is that veteran back with years of NFL experience and relatively little tread on his tires (over his career he's averaged just 12.2 carries per game with the Panthers). But much of the reason for this relatively light workload was due to ineffectiveness -- teammate Jonathan Stewart outplayed him last year to take the lead back job in Carolina outright -- and injury, which isn't exactly an ideal background for someone expected to carry the Steelers' ground game.

So what can we expect out of Williams as he fills in for Bell and starts the year as the lead back in Pittsburgh?

Declining Physical Ability

Father Time seems to have caught up to the Steelers' 32-year old running back.

With a career 4.8 yards per carry average, Williams has seen that number plummet in each of the past four seasons, going from 5.4 in 2011, 4.3 and 4.2 yards per carry in 2012 and 2013, respectively, all the way down to a career-worst 3.5 yards per carry average during his injury-riddled 2014 campaign.

In terms of team contributions, Williams' Rushing Net Expected Points (NEP) per attempt has declined in each of the past four seasons. Peaking at a 0.12 Rushing NEP per attempt average in 2011 -- which had him near the top of the league -- that number has since dropped to -0.02 in 2012 and -0.03 in 2013 before bottoming out at -0.16 last season, which was the sixth worst figure among all backs with at least 50 rushing attempts.

For those unfamiliar, NEP is our signature metric that measures a player's contributions to his team's chances of scoring above or below expectation. If he improves his team's chances of scoring, he receives a positive NEP, and vice-versa. To learn more about it, check out our glossary.

Therefore, it's obvious that each year Williams has contributed less and less, on a per carry basis, to his team's bottom line.

One positive for Williams, however, is his re-dedication to his conditioning in anticipation of a lead back role to start the year. He's shed weight down to the 220-pound mark and is back to a weight closer to the 215 pounds he weighed in as a rookie at the 2006 NFL Combine.

And perhaps thanks to this slimmed-down build, Williams is having a fairly good preseason with the Steelers so far. He's totaled 13 carries for 63 yards (4.8 yards per carry) and one touchdown to go along with one 10-yard reception, suggesting that Williams should be capable of at least filling in for Bell as the team's early down back to start the season.

A Less Than Ideal

However, even if Williams finds the Fountain of Youth in Pittsburgh, beyond his own declining physical skills, Williams must also contend with the recent issues Pittsburgh is dealing with on their offensive line.

Sporting one of the best offensive lines in the NFL last year, the Steelers unit graded out as the league's eighth-best overall and 11th-best in the run blocking department according to Pro Football Focus. But following the broken fibula and ankle suffered by starting center Maurkice Pouncey -- an injury that is expected to sideline the 2011 first round pick and four-time Pro Bowler until Week 12 of this season -- Williams will now have to run behind a line playing at significantly less than full strength.

To add to this, his defensive matchups to start the year aren't doing him any favors either.

Williams opens the season in Week 1 at New England, a team sporting the ninth-best run defense according to our Defensive Rushing NEP per play metric when adjusted for strength of schedule. While this team has lost key members of its secondary, including their three starting cornerbacks in their Super Bowl XLIX victory, they still boast an impressive front seven that includes Chandler Jones, Rob Ninkovich, Dont'a Hightower, Jerod Mayo, and Jamie Collins, a group that will be more than capable of giving opposing run offenses problems all year.

He then follows this up with a game against the San Francisco 49ers, who tallied the 11th-best Adjusted Defensive Rushing NEP per play mark at -0.04. And while the Niners have lost of a number of playmakers due to retirement and free agency, the return of Navorro Bowman to anchor the linebackers and additions of free agent Darnell Dockett and first-rounder Arik Armstead should help keep this run defense stout.

From this it's clear that its anything but smooth sailing for Williams as he begins the year as the team's primary tailback.

Projecting Williams' Workload and Production

As the team's starting tailback in his sophomore season Bell earned a hefty workload, averaging 18.1 rush attempts and 5.2 receptions per game.

I probably don't need to say this, but DeAngelo Williams is no Le'Veon Bell.

In the ground game, if Williams inherits the majority of the work that typically goes to Bell, we can expect him to get roughly 15 to 18 rush attempts in each game depending on game flow. However, given his age and declining skills and the stiff competition he faces during the first two weeks of the year, despite being on an improved offense from a year ago, I would be surprised if Williams improved significantly on his career low numbers from last year to manage anything more than the 4.1 yards per carry he averaged back in 2013.

In the passing game, there's a good chance he could lose some work to the running backs behind him on the depth charts, including Dri Archer, who has caught eight receptions for 47 yards this preseason, including a six-for-47 line in the Hall of Fame game against the Minnesota Vikings. The reason for this is that Williams has never been a great receiver out of the backfield, sporting a career Reception NEP per target of 0.31 and a catch rate of 73.1%, which last year would have ranked him 21st and 26th in these categories, respectively, among all backs with at least 30 targets.

And it's probably unwise to expect Williams to repeat Bell's red zone success as well. Last year Bell scored an impressive nine total touchdowns on 50 red zone touches (six rushing and and three receiving touchdowns on 40 carries and 10 receptions, respectively). In contrast to this, over the last two seasons Williams has managed just one touchdown on 42 red zone attempts (and no receptions).

As the old saying goes, "you can bring a horse to water, but you can't make him drink." Even if Pittsburgh feeds Williams the ball inside the opponent's 20-yard line, he isn't a sure bet to convert on those chances.

Taken altogether, the upside Williams in each of the season's first two games -- if he can garner the 15 to 18 rush attempts typically going to the team's lead back, that is -- lies somewhere between 60 to 80 rushing yards to go along with one to two receptions, and a slight chance of him crossing the goal line in each contest.

And consistent with these expectations, our own projections for him in Week 1 according to our algorithm have Williams at 40 yards on the ground on 11 carries to go along with two receptions and a 24% chance of scoring a touchdown.

Needless to say, if you're rolling with Williams on your fantasy football team to start the year, be ready to temper your expectations.